Fingerprint sensing and matching is a reliable and widely used technique for personal identification or verification. In particular, a common approach to fingerprint identification involves scanning a sample fingerprint or an image thereof and storing the image and/or unique characteristics of the fingerprint image. The characteristics of a sample fingerprint may be compared to information for reference fingerprints already in a database to determine proper identification of a person, such as for verification purposes.
A particularly advantageous approach to fingerprint sensing is disclosed in U.S. Pat. No. 5,953,441 to Setlak and assigned to the assignee of the present invention. The fingerprint sensor is an integrated circuit sensor that drives the user's finger with an electric field signal and senses the electric field with an array of electric field sensing pixels on the integrated circuit substrate.
U.S. Pat. No. 6,289,114 to Mainguet discloses a fingerprint sensor that includes a finger sensing integrated circuit (IC). The finger sensing IC includes a layer of piezoelectric or pyroelectric material placed between upper and lower electrodes to provide electric signals representative of an image of the ridges and valleys of the fingerprint.
A particularly advantageous approach to multi-biometric fingerprint sensing is disclosed in U.S. Pat. No. 7,361,919 to Setlak, which is assigned to the assignee of the present invention and is incorporated in its entirety by reference. The Setlak patent discloses a multi-biometric finger sensor sensing different biometric characteristics of a user's finger that have different matching selectivities.
As portable electronic devices become increasingly smaller in size, space within each portable electronic device is becoming limited for including additional hardware features. For example, fingerprint sensors are becoming increasingly popular for use within an electronic device, and in particular within a portable electronic device or a mobile wireless communications device, such as a cellular telephone, where space may be limited. Moreover, including a fingerprint sensor in a portable electronic device may increase the overall device footprint. Additionally, as the use of a fingerprint sensor in a portable electronic device becomes increasingly popular, it may be desirable to include additional features.
One particular approach is disclosed in U.S. Patent Application Publication No. 2006/0181521 to Perreault et al., which discloses a system for dynamically illuminating sensors. A dynamic illuminator is positioned next to a contact surface of a touch sensor and is used to display a status of the touch sensor.
Another approach is disclosed in U.S. Patent Application Publication No. 2007/0133847 to Ogura. Ogura discloses an image input device and includes a light guide and covers infrared light emitting diodes surrounding the periphery of a light sensor. The light guide guides emitted light to a finger placed on the light sensor.